Ice cores clearly demonstrate the close relationship between atmospheric CO2 levels and temperature, as seen below.
This relationship has been well understood by geologists for longer than Al Gore has been alive.
As ocean temperatures rise, the solubility of CO2 in seawater declines. Thus increasing ocean temperature moves CO2 from the ocean into the atmosphere, and decreasing ocean temperatures move CO2 out of the atmosphere and back into the ocean. As you can see in the graph below, a 10C shift in temperature causes about 30% reduction in dissolved CO2. Closely corresponding to what we see in the measured ice core graph above.
Ice ages are driven by orbital cycles
of the earth, and as ocean temperatures change, atmospheric CO2 levels respond - in accordance with the laws of chemistry. The relationships are uncontroversial.
Unfortunately, some educators besides Al Gore have taken liberties with the ice core data. Children's global warming author Laurie David published the incorrect graph below, which shows that CO2 levels changed prior to the temperature levels. The graph misleads children into believing that ice ages are driven by changing CO2 levels, rather than the other way around. It is difficult to understand how this error could have happened accidentally.
This week is National Engineering Week in the US, when elementary school children are encouraged to learn math and science. Don't they deserve and need accurate information? Are Laurie David's book and Al Gore's movie acceptable in a science classroom?
Whether or not you believe that the burning of fossil fuels significantly affects the earth's temperature, the ice core data offers no evidence to support that - no matter how big the graph is.
Part 1 of this series is here